Remove file name in snippet lists

At the moment, wherever we show a list of snippets (dashboard, explore, etc..) we show the file name in the snippet.

Now that the file name comes from the repository instead of the database, showing the file name will require 3 Gitaly calls (to check if the snippet has a repository, check the repository ref, and retrieving the files). Considering that we show around 20 snippets, that means we will make 60 calls to Gitaly minimum.

Since we're going to allow snippets to have several files, at some point we will remove that from these views. So, why don't we do it now before we migrate all snippets to repositories and avoid hurting the performance?